The cornea, the outermost window of our visual system, is vulnerable to various types of infections and diseases. Corneal disease is one of the leading causes of visual deficiency and blindness.!There are nearly 5 million bilaterally corneal blind persons worldwide, and an estimated 23 million people affected by unilateral corneal blindness globally. In a conservative estimate, corneal diseases affect nearly 300,000 people in the United States, with Fuchs? dystrophy affecting 4% of people aged over 40, and 1 in 2,000 Americans affected by keratoconus. Since many corneal diseases can only be distinguished at the micrometer scale, there is a strong need for imaging tools that can noninvasively visualize the cellular changes in the cornea in vivo, to assist clinical diagnosis, evaluate progression of diseases, and treatment. We have developed a 3D high-definition imaging instrument based on Gabor-Domain Optical Coherence Microscopy (GD-OCM) for noninvasive visualization and quantitative characterization of the cornea over a large field of view. Our data suggest that GD-OCM has the following key advantages over existing in vivo corneal imaging techniques, which include optical coherence tomography (OCT) and confocal microscopy: 1) 6-10x increase in field of view compared to existing confocal microscopes used in clinics worldwide ? this will lead to more accurate qualification of the corneal tissue, since a larger area can be assessed; 2) non-contact operation, unlike confocal microscopes, greatly reducing patient discomfort and eliminating risks of corneal damage; 3) high-definition cross-sectional imaging at an order of magnitude better lateral resolution than OCT; 4) 3D imaging capability at the cellular level over the entire thickness of the cornea? this will enable advances in understanding the progression of the diseases. We hypothesize that GD-OCM can accurately conduct all the assessments currently performed with OCT and confocal microscopy, and additionally provide 3D visualization of the cornea structures over the full depth of the cornea for additional tissue characterization and diagnostic aid. In addition to aiding early diagnosis of corneal disease, the proposed GD-OCM instrument will aid in pre- and post-operative screening for refractive surgery, transplant, drug therapies, monitoring wound healing, corneal nerve assessment, and prevention of stromal rejection. We envision that in the future the GD-OCM instrument enabled by this Phase I SBIR proposal will provide the early foundation for an image-guidance method to assist clinicians in the assessment and treatment of corneal diseases and other diseases affecting the anterior segment of the eye, including diabetes and glaucoma.